1. Field of the Invention
The present invention relates to a block supercapacitor, a manufacturing method thereof, a composite as an electrode material thereof, and a method of preparing the same. More particularly, the present invention relates to a block supercapacitor having an in-plane structure with improved performance, a manufacturing method thereof, a composite suitable for use as an electrode material thereof, and a method of preparing the composite.
2. Description of the Related Art
Typically, a supercapacitor, which is also referred to as an electric double layer capacitor (EDLC) or an ultra-capacitor, is an energy storage device using a charging phenomenon based on a surface chemical reaction or simple ion movement to an interface between an electrode and an electrolyte, unlike batteries based on chemical reactions.
Specifically, a supercapacitor is composed of electrodes attached to conductors and an electrolyte solution incorporated therein, and employs a pair of charge layers having opposite polarities (an electric double layer) formed at the electrode interface. Such a supercapacitor enables quick charge/discharge and exhibits high charge/discharge efficiency. Furthermore, the supercapacitor manifests semi-permanent cycle life properties, without the need for repair due to very low degradation by the repetition of charge/discharge operations. Hence, the supercapacitor may be utilized as an auxiliary battery or an alternative to batteries and is thus receiving attention as a next-generation energy storage device.
The capacitance of the supercapacitor is determined by the charge amount accumulated in the electric double layer. The larger the electrode surface area, the higher the charge amount. A commercially available supercapacitor is composed mainly of activated carbon electrodes. To obtain higher power storage capacity, thorough research is ongoing into novel electrode materials. An example of such an electrode material is graphene.
Graphene refers to a carbon structure made up of a two-dimensional (2D) nanosheet single layer of carbon atoms arranged in hexagonal honeycomb lattices, and is regarded as a promising electrode material because of very large specific surface area per volume and outstanding electronic conductivity. However, graphene electrodes developed to date for use in supercapacitors are manufactured in such a manner that a mixture including graphene and graphene oxide is pressed or graphene ink is dropped onto carbon electrodes and then dried, and thus the structural features of graphene are not used properly.